Selection Fundamentals

Two things selections do

Selections have two main purposes

1. They allow you to constrain a change (such as a filter, image adjustment, etc.) to one certain part of a picture.
2. They are the first step in creating an alpha channel, which tells Photoshop which part of an image to throw away or make transparent.

The Marquee

Selected parts of images are represented by a set of moving dashed lines called a marquee (some call them marching ants). Everything inside the marquee is considered selected and is available for changes within Photoshop. Everything outside the marquee is considered protected and will not change when filters or adjustments are applied to the image. In the example to the right, the parrot was selected, then the hue was changed. Everything within the selection turned green but the background remained the same.